Process of extracting precious metals.



No. 745,490. PATENTED DEC. 1, 1903'.

T. J. GRIER. PROCESS OF EXTRAGTING PRECIOUS METALS.

APPLIOATION FILED FEB. 14. 1903. no MODEL,

w a bmiiw f WITNESS" Extracting Precious Metals;

ceive slimes UNITED, STAT S Patented December 1, 1903.

PATENT OFFICE.

THOMAS. JOHNSTON GRIER,

OF LEAD, SOUTH DAKOTA.

SPECIFICATION forming part of Letters P atent No. 745,490, dated December 1, 1903.

Application filed February 14, 1903. Serial No. 143.442 (No specimens.)

To ail whom it may concern.-

Be it known that I, THOMAS JOHNSTON GRIER, a citizen of the United States, residing at Lead, in the county of Lawrence and State of South Dakota, have invented certain new and useful Improvements in Processes of and I do declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same, reference being had to the accompanying drawing, and to the letters of reference marked thereon, which forms a part of this specification.

This invention relates to a new and useful process for extracting precious-metal values from slimes by the use of cyanid of potassium, and comprises an upward leaching slime process whereby one liquid is raised by another of greater density without the mixing of the same; and it consists in various steps, which will be hereinafter fully described and then specifically defined in the appended claims.

I have illustrated an apparatus whereby the various steps of my process may be carried out, and in which drawing I have shown asectional view through the apparatus, show ing the various parts in elevation.

Reference now being bad to the details of the drawing by letter, A designates an ordinary settling-tank which is adapted to re from a millthrough a pipe B, which empties into the cylindrical receptacle O, having a perforated bottom 0. The slimes coming from the mill are strained through the bottom of said cylindrical receptacle and will settle in the bottom of said tank, and the clear water will rise to the top and overflow. In the bottom of the tank A are outlets A, there being any suitable number of these provided, which communicate with an exit-pipe D, which has a valve therein regulated by the hand-wheel 1), whereby the feeding of the slimes from the settling-tankthrough said pipes may be regulated. The slimes as they pass through the pipe D empty into the leaching-vat E. Before the slimes, however, enter the leaching-vat they are acted upon by a neutralizing solution which is sprayed into the pipe D through the passage-way F, which is controlled by a valve F and leads from a receptacle F containing the protective solution, consisting of water mixed with a sufficient quantity of lime necessary to neutralize the acid contained in the slimes; Leading from the tank near its upper portion is a valveregulated exitpipe G, through which the slimes may run to an adjacent tank (not shown) after the vat E is filled. Positioned within the lower portion of the vat E is a false bottom H, with a space intervening between the same and the bottom proper of the vat, and said false bottom is provided with a series of perforations h, and underneath said false bottom and between the same and the bottom of the vat is positioned a coil K, having perforations therein and through which coil cyanid of potassium is adapted to pass, coming through pipe K from a receptacle N, Which has a valve-regulated pipe N communicating between the same and said pipe K. Said coil K is also utilized for the purpose of introducing a salt (NaCl) solution at a proper time during my improved process from the receptacle M through the valve-regulated pipe M, and again the pipe K and coil K are utilized to convey air under pressure from the air-pump, (indicated by letlerO) through the valve-regulated pipe 0.

Leading from the portion of the vat E below the false bottom is a pipe E and also a second pipe E leads from the vat at a location immediately above said partition, and through which pipe the sediment and contents of the vat may be drawn.

In order to reduce the density of the liquid in the upper portion of the vat E and for the purpose of expediting the process of extracting the metals from the slimes, it is my purpose to introduce a steam-pipe Q in the vat, through which steam is allowed to pass. Said pipe may be arranged so that it may be lifted out of the vat when desired.

The various steps of my process which may be accomplished by the apparatus described consist in first introducing slimes, as before stated, in the settling-tank A, and as said tank fills the solid portions of the slimes settle at the bottom, the clear water flowing over the top. When said tank is partially filled, preferably the depth of the tank, the valve controlled by the hand-wheel D is opened sufficiently to draw off as much of the solid matter in the tank as it receives from the mill. By properly adjusting said valve the apparatus may be regulated to draw off the solid matter at the rate of its reception from the mill, thus making the apparatus continuous in operation. As the thick slimes make exit from the pipe D they are sprayed with the protective solution, consisting of water mixed with a sufiicient quantity of lime to neutralize the acid contained in the slimes, and afterward flow into the vat beneath. When the vat is full, the slimes are diverted to the next vat, and a solution of cyanid of potassium under gentle pressure is allowed to flow from the tank N through the pipes N and K and coil K and to issue through the perforations of the coil K into the bottom of the vat E between its false and real bottoms. On account of the greater density of the solution of cyanid of potassium than the water the watery part of the slimes is raised and caused to overflow the cyanid solution, not materially mixing with the water which it displaces. As soon as the clear water has all overflowed the feeding of the cyanid of potassium is cut pressure of compressed air is allowed to pass through the pipes O and K pressed-air chamber or pump 0 and to issue through the perforations of the coils K and to agitate the slimes in the vat E. When a satisfactory extraction of the precious-metal values has been accomplished by these steps of the process, the supply of air under pressure is shut off and the inexpensive and uninjurious salt solution contained in the tank M and which is more dense than the cyanid solution is allowed to pass through the pipes M and K and to issue through the perforated coils K and to enter the vat through the perforated false bottom. By the introduction of the salt solution the cyanid solution will rise to and overflow the vat, owing to the salt solution having a greater density than said cyanid solution. When the cyanid solution has been overflowed, the vat is ready for sluicing. Before sluicing, however, all of the salt solution above the slimes and between the bottoms may be drawn off and used again and again. To Win values from the cyanid solution which overflows, any of the practices common in the art may be followed.

In order to reduce the-density of the liquid in the upper portion of the vat, steam may beintroduced through the pipe Q in theleaching-vat above the false bottom, by which step the liquid is assisted in risin Having thus fully described my invention, what I claim as new, and desire to secure by Letters Patent, is

1. The process of extracting precious metals from slimes, consisting in subjecting slimes to the action of a cyanid solution, whereby the watery portions of the slimes may be disoff and a light from the com-- watery portions of the slimes to placed by the cyanid solution, the latter being of greater density than the water of the slimes, then treating the charge with com pressed air and afterward displacing the cyanid solution with a salt solution of greater density than the cyanid solution, as set forth.

2. The process of extracting precious metals from slimes, consisting in subjecting the slimes to the action of a cyanid solution under pressure, whereby the watery portions of the slimes may be displaced by the cyanid solution, the latter being of greater density than the water of the slimes, then treating the charge with compressed air and afterward adding a salt solution in such a manner as to displace the cyanid solution, said salt solution being of greater density than the cyanid solution, as set forth.

3. The process ofextractingprecious metals from slimes, consisting in spraying the thick slimes with a protective solution to neutralize the acids therein, of introducing a cyanid-ofpotassium solution in the slimes to displace the watery portions thereof, the latter being of less density than the cyanid solution, afterward treating the charge with air under pressure, and adding a salt solution under pressure in such a manner as to displace the cyanid solution, as set forth.

4. The process of extracting precious metals from slimes, consisting in subjecting the slimes to a protective solution to neutralize the acid therein, then introducinga cyanid-ofpotassium solution into the slimes to displace the Watery portion thereof, the latter being of less density than the cyanid solution, of treating the charge with compressed air and afterward introducing in the Vat, in Which the slime is contained, a salt solution in such a manner as to displace the cyanid solution, and heating the contents of the vat above its false bottom for the purpose of reducing the density of the upper stratum of liquid, as set forth.

5. The process of extracting precious metals from slimes,consisting in directing the slimes into a settling-tank, drawing 0d the thicker portions of the slimes and depositing the same into a leaching-vat, of introducing a cyanid solution under pressure through perforations in the false bottom of the vat, causing the be displaced by said cyanid solution, then treating the charge with air under pressure,and afterward introducing through the false bottom of the vat a salt solution of greater density than the cyanid solution to displace the latter, as set forth. a

In testimony whereof I hereunto affix my signature in presence of two Witnesses.

THOMAS JOHNSTON GRIER.

Witnesses:

WARNER MooDY, CHAMBERS KELLER. 

